The many varieties of the world’s manufactures—­one might almost call them wonders—­are now so numerous, that to bring any particular one in a single form before this meeting is a matter of no easy nature.  To-night, however, I have ventured to single out, and have the pleasure of bringing before you, the steam-engine, as the prime mover at present of our workshops and manufactories, as also the grand motive power of our railways, now so different from the time when the great Stephenson was said to be mad, because he thought it possible to drive a train at fifteen miles an hour.  For the first serviceable use of this grand machine we are indebted to the great James Watt.  He it was who first wrought it so as to be under the useful and entire control of man, from what it was in the time of Hero of Alexandria, about 120 years before Christ.  Our engineers have, since Watt’s time, improved upon it year by year, till at the present day, instead of having to go in a mail-coach from London to Edinburgh, which formerly took fifty hours, we now go in the express train in ten, a distance of 420 miles.  If beyond this ten hours, we grumble, and ask guards, porters, &c., at the various stations, “What has made the train so late to-day?” forgetting that just before the railways were first opened, the great Stephenson was urged not to say too much as to the supposed power of the locomotive, in case the cause of railways might be damaged.  This was only some forty years ago, and it shows us how times are changed, for in the present day we consider thirty miles an hour anything but a fast train.

The history of the steam-engine is a subject on which so much has been written in books and magazines now before the public, that what I am about to offer, though pretending nothing new, yet I hope may be looked upon as containing something useful as well as instructive, both to the practical and the amateur mechanic.  I shall therefore, in as small a compass as possible, trace the steam-engine from its first and early stages up to its present perfect state as our grand motive power.  The first mention made of the vapour of water, as formed by the action of heat upon it, is found to be as far back as 120 B.C., when one Hero of Alexandria employed this vapour for the purpose of driving a machine.  It is a well-known fact that when water is brought up to a certain degree of heat, called the boiling-point, that it sends forth a vapour, the elastic properties of which, when in an open vessel, are not perceived—­as, for instance, in a common pan—­yet if the vessel is closed or shut up at the top, you will find that the vapour acquires such a degree of elastic force, that, if not allowed to escape by fair means, it would soon make a way or vent for itself by bursting whatever vessel it was contained in.  Steam is thus highly elastic, but when separated from the fluid out of which it is generated, it does not possess a greater elastic force than the same quantity of air.  If, for example, a vessel is filled with steam only at 212 deg., it may be brought to a red heat without fear of bursting; but if water is also in the vessel, each additional quantity of heat causes a fresh quantity of steam to be generated, which adds its elastic force to that of the steam already in the vessel, till the constantly accumulating force at last bursts the vessel.